HP Car 3490A manual @ \ - O @ @ o o, Test Oscillator, MU L T I M E T E R h p 3 4 9 O a, 6 5 2 a

Section V			PERFORMANCECHECKS
TEST OSCILLATOR
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Model3490A

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Figure5-6. AC Voltmeter Input lmpedanceTest.

with the Sample/Hold performance tests. Refer to Paragraph5-9.

$32. Sample/HoldBC Mea$rement AecuracyTest.

5-33. A dc standard (-hp- 7a0B) is required for this procedure, which checks the dc voltage accuracy of the Sample/Hold circuits to the 90-day specification in both Track/Hold and Acquire/Hold operation. Accuracy is not specifiedfor the .l V range.

Connect Guard to Input Low or damageto the instrument mav result.

a.Set 3490A FUNCTION to DC, RANGE to I V, SAMPLE/HOLD to TRACK/HOLD, SAMPLE RAT.A, fully clockwise.

b.Connect dc standardbetweeninput High and Low terminals.

c.Select3490A rangesand dc standardpositiveand negativeoutputs listed in Table 5-6. Display should be within limits shownin eachcase.

Table5-6. Sample/HoldDC AccuracyCheck.

3490A	DC Standard	Display Limits
Range	Output

r0.10000V r 0.0998to 0.1002V

1V r 0.50000v ! 0.4998to 0.5002 V

r1.00OO0V t 03997 to 1.0OO3V

1 1.00000v 100998 to 01.002V

1 0 v r 5.00000 v + 04998 to 05.002 V

I 10.0000V ! 09.997to 10.OO3V

r l0.0O0OV t 009.98to 010.02V

100v r 50.0000 v t 049.98ro 05O.O2V

r 100.000v I 099.97to 100.03V

1100 . 000v t 0099"8to 0100.2 V

1000v t 500.000v ! 0499.8to 0500.2 V

'+ 1000 . oov r 0999.7to 1OO0.3V

*lf -hp-74OB DC Standard is used, do not apply negative \roltage greater than - 5OOV.

connäct StretchedPulseOutput (J7 pin l0) to External Enclode(J7 pin 28).

b.SEt 3490A FUNCTION tO DC, RANGE tO IO V, SAMPLE/HOLD to TRACK/HOLD, SAMPLE RATE to HOLD.

d.Set SAMPLE/HOLD to ACQUIRE/HOLD and repeatstepc.

$34. Sample/HoldResponseTest.

5-35. A function generator (-hp- 3310A), an oscillo- scopewith delayedsweepand delayedgateoutput (-hp l80C/l80lAll82lA), a silicon diode, and a l0kh resistorare requiredfor this test, which verifiesthat the Sample/Holdcircuitswill respondto a stepinput voltage within the stated acquisition time. The Delayed Gate

Output from the oscilloscopemust be a negative-going pulse at least 30 nanosecondswide and havins an amphtudeof I to 100 V.

f,. Conne''requipmentas shown in Figure5-7.If the -r490A ha: BCD Remote Expand Option 020, also

c.Set oscilloscopecontrols for External Trigger, negative slope, and Main sweep. Set Main sweep to

.1 ms/div.,Delayedsweepto I ps/div.

d.Set function generatorto squarewave,frequency to I kHz, and adjust output level for 20 V peak-to-peak signalasdisplayedon oscilloscope.

e.Adjust oscilloscopedelay control so that intensi- fied trace begins approximately 450 ps after negative- going transition of squarewave. Note 34904 reading, which shouldbe nearzero.

f.Adjust delay so that intensified trace begins approximately125ps after negative-goingedgeof square wave (stated maximum acquisitiontime for l0 V range is 128ps). Readingshould be within 1 0.001 V of the readingnoted in stepe.

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